Sort on IDSource column ?

Hi!

I would like to know whether there is a trick to sort a GridView based on a column that contains IDSource information. For example, if I have a GridView with a column populated using Eval("AddressIDSource.StreetName"). Is it possible to sort the GridView based on the Street Name?

Cheers!

 JF
 

Hi,

No, unfortunately the ASP.net GridView does not support sorting on complex objects. You could workaround this situation by creating a property on your object for the StreetName

[Bindable]
public string AddressIdStreetName
{
  get{ return AddressIDSource.StreetName; }
  set { AddressIDSource.StreetName = value; }
}

Hi!

Thanks Robert! I had thought about this, but it would be a last resort solution for us, since we use look-up tables everywhere and we need this in every GridView.

Do Strongly Typed Data Sources support sorting on complex objects? The Data Source would need to perform a JOIN internally I guess. Is this supported? I could then apply the sorting on the Data Source and rebind the GridView.

Cheers!

JF
 

It's the actual GridView that's to blame and not the bound data.  I do believe the winforms gridview allows it so it's just a matter of changing the gridview so that supports it.

Hi!

In EntityPropertyComparer.cs, we find the following method:

        public int Compare(object x, object y)
        {
            object a = x.GetType().GetProperty(PropertyName).GetValue(x, null);
            object b = y.GetType().GetProperty(PropertyName).GetValue(y, null);

            if ( a != null && b == null )
                return 1;

            if ( a == null && b != null )
                return -1;

            if ( a == null && b == null )
                return 0;

            return ((IComparable)a).CompareTo(b);
        }

Would it be possible to modify this method's implementation so that it would possible to use a PropertyName like 'CustomerIDSource.CustomerName'. I guess, what would have to be done is to split the Property name on the period character and find the type and value of the last object (CustomerName in this case). I don't have any experience with reflexion. Sorry for my ignorence.

If such a comparer would be feasible, would it be possible then to get a GridView to use it?

Cheers!

JF
 

What about replacing the above routine by the two following ones, in order to support complex objects?

        public object getObj(object x)
        {
            object a = string.Empty;
            string[] PropertyParts;
            char[] delimiterChars = { '.' };
            PropertyParts = PropertyName.Split(delimiterChars);
            foreach (string propertyPart in PropertyParts)
            {
                a = x.GetType().GetProperty(propertyPart).GetValue(x, null);
                x = a;
            }

            return a;
        }

        /// <summary>
        /// Compares 2 objects by their properties, given on the constructor
        /// </summary>
        /// <param name="x">First value to compare</param>
        /// <param name="y">Second value to compare</param>
        /// <returns></returns>
        public int Compare(object x, object y)
        {
            //object a = x.GetType().GetProperty(PropertyName).GetValue(x, null);
            //object b = y.GetType().GetProperty(PropertyName).GetValue(y, null);
            object a = getObj(x);
            object b = getObj(y);

            if ( a != null && b == null )
                return 1;

            if ( a == null && b != null )
                return -1;

            if ( a == null && b == null )
                return 0;

            return ((IComparable)a).CompareTo(b);
        }

Cheers!

JF
 

Hi,

Has anyone successfully implemented this? I'm wondering how to get my GridView to use the EntityPropertyComparer. Thanks for any help.

I tried adding the [Bindable] attribute but it still did not work.  There are some overloads to the constructor, what should be in the overloads to support this?